Cartridge type tube and fin heat exchanger

ABSTRACT

A true counterflow heat exchanger of the tube and fin type having a cartridge design in accordance with which the heat exchanger unit may be removably installed in a housing cavity while retaining its counterflow principle of operation. A manifold member at an inner end of the unit is formed for free flow of a first fluid therethrough and for confined flow of a second fluid to receive such second fluid and return it to the opposite or outer end of the unit.

United States Patent 1191 Fernandes 1451 Apr. 17, 1973 CARTRIDGE TYPE TUBE AND FIN HEAT EXCHANGER (7 57 Inventor: joselih E. Fernandes, Centervill e,

1 Ohio [73] Assignee: United Aircraft Products, Inc.,

Dayton, Ohio 221 Filed: June 17, 1971 [21] Appl.No.: 153,991

52 us. c1 ..165/l58, 165/166 51 1m. (:1 ..F28b 9/02 58 Field 61 Search ..165/152, 153, 164-166, 165/74, 75

[56] References Cited UNITED STATES PATENTS 2,877,000 3/1959 Person 165/166 X 3,590,909 7/197! Butt 165/166 4/1954 Huet .l65/l66X 12/1971 Tiefenbacher ..l65/ 165 Primary Examiner-Charles J. Myhre Assistant Examiner-"Iheophil W. Streule, Jr. Attorney-J. E. Beringer ABSTRACT A true counterflow heat exchanger of the tube and fin type having a cartridge design in accordance with which the heat exchanger unit may be removably installed in a housing cavity while retaining its counterflow principle of operation. A manifold member at an inner end of the unit is formed for free flow of a first fluid therethrough and for confined flow of a second fluid to receive such second fluid and return it to the opposite or outer end of the unit. I

14 China, 8 Drawing Figures PATENTED APR 1 7 I975 SHEET 1 OF 2 INVENTOI? JOSEPH F. FERNANDE S HIS ATTORNEY PATENTEBAPR 1 H913 SHEET 2 BF 2 INVENTOR JOSEPH F. FERNANDES HIS ArrbR/vn BACKGROUND OF THE INVENTION This invention relates to heat exchangers and particularly to tube and tin heat exchangers having a counterflow manner of operation and adapted for use as an insert or cartridge type device. Although not so limited, the invention has particular application to intercoolers useful in air compressors or the like. In referring to an air" compressor it will be understood that this term is intended to be inclusive of gas compressors generally and not only those operating upon atmospheric air. References to air are intended to identify any air-like gaseous fluid.

In a current state of the air compressor art, intercoolers are required to extract large amounts of heat from flowing compressed air. At the same time, compressor designs have become increasingly less tolerant of intercoolers which meet higher heat transfer requirements with corresponding increases in their physical dimensions. A demand exists for compact, high performance heat exchangers, especially when it is required that the heat exchanger function as an insert or cartridge device to be accommodated in a provided cavity in a compressor housing.

SUMMARY OF THE INVENTION The instant invention has in view a generally new heat exchanger which though adaptable for use as a cartridge device employs a true counterflow principle of operation and is otherwise constructed for high performance without excessive size, bulk and weight.

It is comprised of tubes which are supported between header plates to conduct a coolant such as water. The tubes provide expansive heat transfer surface overlaid by fin strip means. In effect the tubes are sandwiched between layers of tin strips, each strip composing multiple fin corrugations. Air enters through openings in one of the header plates and flows through passes defined by the fins to discharge laterally of the unit upon encountering the inner face of the other header plate. A manifold member at the air inlet end of the unit is constructed to allow air flow therethrough and is chambered to accept the flowing coolant and return it to the opposite end of the unit as defined by the described other header plate. Among the features of the invention is one achieving a total air seal by means including a sealing contact of fin corrugations with the tube exteriors whereby to prevent lateral leakage of flowing air between the tin strip means and the tubes.

To provide a heat exchanger so constructed and so characterized is an object ofthe invention.

Other objects and structural details of the invention will appear from the following description, when read in connection with the accompanying drawings. wherein:

FIG. 1 is a view in longitudinal section, partly diagrammatic, showing a heat exchanger in accordance with the illustrated embodiment of the invention installed as a cartridge in an air compressor or the like, FIG. I being a view taken substantially along the line 1-1 of FIG. 2;

FIG. 2 is a view similar to FIG. I, being taken substantially along the irregular line 2-2 of FIG. 1;

FIG. 3 is a view in cross section, taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a view in cross section, taken substantially along the line 4l-4 of FIG. 2;

FIG. 5 is a view in cross section, taken substantially along the line 5-5 of FIG. 2;

FIG. 6 is an enlarged detail view showing the manner I in which multiple tube elements in stacked relation make up a tube means;

FIG. 7 is a fragmentary detail view showing a portion of a fin strip abutting a header plate; and

FIG. 8 is an exploded perspective view, showing in fragmentary form a modified tube means.

Referring to the drawings, for illustrative purposes the invention is disclosed as embodied in an intercooler for air compressors. A compressor body 10 is formed with a bore 11 which opens through an outer face 12 of the body. A counterbore l3 defines a seat 14 near the bottom of bore 11. Beyond seat 14, bore 11 communicates through a passage 15 with a source of air which as a result of being compressed has absorbed substantial amounts of heat. In the course of movement of the air outwardly of the bore 11, in the direction indicated by the arrows 16 in FIG. 1, it is desired to extract excessive heat from the air.

To this end, there is inserted in the counterbore 13 a heat exchanger unit 17. A core of unit 17 comprises longitudinally spaced apart header plates 18 and 19 between which are laterally spaced apart tube means 21-26. The tube means 21-26 are identical to one another. Each comprises a stacked series of individual tube elements 27 (FIG. 6). Each element 27 is elongated in a longitudinal sense and made rectangular in cross section to provide therein a through flow passage 28. The tube elements are made of a material which is readily heat conductive and which lends itself to bonding to other parts by a soldering or brazing type operation. The tubes may, for example, be of all copper or of a copper plated steel construction. In effect, the several stacked elements 27 comprise a single tube and each tube means 21 through 26 will hereinafter for convenience be described as a tube.

The header plate 18 is made of a materialcompatible with the tubes 21-26 in the sense of being readily soldered or brazed thereto. It is formed with a lateral series of slots 29 each accommodating an end of a tube 21-26. The header plate 19 is constructed similarly to the plate 18. It has a lateral series of slots 31 corresponding to the slots 29 and adapted to align therewith. In addition, however, the plate 19 is formed with a lateral series of vertically elongated openings 32 which are in alternating relation to the slots 31. Further, the header plates 18 and 19 are formed with respective openings 33 and 34 aligned with one another and offset relatively to the tubes 21-26. Extending between and interconnecting the openings 33 and 34 is a tube 35.

The described core is completed by strips 36 of a corrugated fin material which dispose between the external walls of tubes 21-26 and define in connection therewith extended heat transfer surface. The strips 36 orient longitudinally of the tubes so that the corrugations thereof at one end face the header openings 32 and form continuing flow passes for air moving outwardly from the bottom of bore 11. There may be single fin strip disposed between each adjacent pair of tubes, or, as in the illustrated instance, there may be a pair of strips in a back-to-back relation so disposed between each pair of adjacent tubes. In the latter instance, a thin plate 40 may be used to separate the strips of each pair and to avoid telescoping of the corrugations. In any event, the fin strips are constructed to have a corrugation height which insures that the peaks and valleys of the corrugations are in lightly compressive contact with the tubes when installed therebetween. Still further, the fin strips have a length less than the length of tubes 2126 and are longitudinally offset so that at their one ends the fin strips abut against the inner face of header plate 19 and at their other ends are longitudinally spaced from the inner end of header plate 18. Between plate 18 and the adjacent ends of the fin strips spaces 37 are formed between each pair of tubes. The spaces 37 are in free communication with the counterbore 13 surrounding the tubes I 21-26. The body provides an air outlet 38 also communicating with counterbore 13.

In assembling the heat exchanger core, tube elements 27 are stacked one upon another. Each such stacked row, constituting a tube means, is placed in opposing slots 29 and 31 of the header plates 18 and 19,

the tubes and header plates being so relatively disposed I that the tube ends project through but not substantially beyond the respective plates. Fin strips 36 are disposed between the tubes or tube means which present expansive wall surface to be contacted by the fin strips. The latter approximately correspond in width to the tubes and are relatively foreshortened in a longitudinal sense, as previously seen. The fin strips are offset to contact the header plate 19 and define spaces 37. The parts so assembled are fixtured or otherwise held against relative movement, and, while so held, are subjected to a brazing or soldering operation in which the several parts are unitarily joined to one another. In the process the ends of tubes 21-26 are joined to the margins of slots 29 and 31 and seal against a flow of fluid through such slots around the tubes. Also, the peaks and valleys of the fin strips 36 are joined to the expansive wall surfaces of contacted tubes 21-26 and form therewith a seal and a bond. The flow passages defined by adjacent fin corrugations accordingly are sealed from one another, precluding a lateral flow or leakage of the air as it moves lengthwise of the fin strips. In the same or in a separate operation, tube 35 may be mounted in header plate openings 33 and 34 and sealed at its ends therein.

in an installed position of the described core, the intercooler assembly is completed by a manifold member 39 at what may be considered the air inlet end of the unit and by a manifold member 41 at what may be considered the coolant inlet end. The manifold member 41 has an inwardly facing recessed formation 42 defining a chamber 43 communicating with the tubes 21-26 at their one ends, or more particularly with the passages 28 in the individual tube elements 27. An inlet boss 44 opens into the chamber 43 and provides a means by which water or other coolant is brought to the intercooler. For convenience of description the coolant will hereinafter be referred to as water. Another boss 45 projects from the manifold member 41 and serves as the water outlet. At an inner end, the boss 45 is open and aligns with header plate opening 33. The manifold member 41 has a radially projecting flange 46 adapted to seat to the face 12 of the compressor body 10. A

resilient gasket 47 is interposed between the flange 46 and face 12 and between flange 46 and header plate 18. The gasket is suitably slotted and cut to define apertures registering with the slots 29 and with opening 33.

The manifold member 39 has a radial flange portion 48 adapted to engage in and abut against the seat 14 at the bottom of counterbore 13. Inwardly of the flange 48, member 39 is formed with a laterally spaced apart series of projecting ribs 49 which are located in alternating relation to through openings 51 in the manifold member. The latter substantially correspond in number and configuration to the header plate openings 32 and the manifold member is so angularly oriented as to cause openings 32 and 51 to register with one another. To aid in such angular orientation, a dowel pin 52 may be used to obtain a fixed angular relationship between the header plate 19 and manifold member 39. The ribs 49 are internally slotted in a longitudinal sense to define internal flow passages 53. These open through an inner front face of the manifold 51, and, at their lower ends terminate in a manifold or water collection chamber 54. Properly oriented relatively to the header plate 19, the slots or passages 53 of the manifold member 39 align with and form continuations of the water carrying passages 28 which make up the open in teriors of tubes 21-26. A gasket 54 is placed between the header plate 19 and manifold member 39 and is slotted and cut to have apertures therein corresponding to the slots 31, openings 32 and opening 34.

The manifold member 39 may be pre-assembled to the heat exchanger core outside the compressor body 10. Under this circumstance, in the installation of the heat exchanger, the core and member 39 are inserted as a unit into counterbore 13 until the manifold member engages against seal 14. Adjacent to the seat 14 is an annular groove containing an O-ring seal 55. The latter contacts the periphery of flange portion 48 and inhibits an escape of pressure fluid from the bottom of bore 11 around the manifold member. In a separate or as a part of the same operation, manifold member 41 is applied to the outer end of the heat exchanger core and bolts 56 or other means are used to fasten the manifold to the face 12. In the process, an axially compressive force is exerted upon the heat exchanger core which is effectively clamped between manifold member 17 and seat 14. Gaskets 47 and 54 are compressed and effective seals defined around the several openings in the header plates. For access to the tubes 21-26, for cleaning or for repair, the manifold member 17 is readily removed. The entire core unit may similarly be removed, after detachment of manifold member 17, with or without the manifold member 39. The latter may be permitted to remain within the compressor bore, to be reengaged when the same or a new core is reintroduced into the body, through the aid of dowel means 52.

In the operation of the intercooler water is brought to manifold chamber 43 by way of inlet boss 44. In chamber 43, the water has common communication with the ends of tubes 21-26 and flows in unison and in a single pass therethrough. At opposite ends of the tubes, the water enters respective registering passages 53 in manifold member 39 and is constrained thereby to flow downwardly or at right angles to its previous direction of movement to collection chamber 54. The

latter communicates through header opening 34 with the tube 35 so that collected water is returned toward the front of the unit where it reaches outlet boss 45 and is conducted away from the intercooler. Heated, com pressed air reaches the bottom of bore 11 by way of passage 15. In bore 11, the air has access around the ribs 49 to openings 51 in the manifold member. Passing through these openings and through registering openings 32 in the header plate 19, the air enters upon flow passages as defined by the corrugations of fin strips 36. The air is conducted along these corrugations lengthwise of the fin strips to discharge into spaces 37 and to pass freely from these spaces out of the counterbore 13 by way of outlet passage 38. in the process of flowing along fin strips 36, heat transfer takes place by a conduction-convection process between the flowing air and the water in tubes 21-26. A portion of the heat contained in the air is absorbed into the cooler water with the result that the air as it discharges through outlet 38 is substantially reduced in temperature. The,

heated water may be recirculated for reuse or suitably discharged to waste. v

The construction and arrangement of parts provides for true counterflow operation in a cartridge type heat exchanger. The water and air flows occur in a single pass through the heat exchanger and in directions opposite to one another, yielding maximum heat transfer benefits. A further feature of the invention resides in the accomplished total air seal. The O-ring seal surrounding manifold member 39 and the individual fin seals at each of the corrugations of the fin strips 36 effect positive control of air movements. After the air en ters the inlet manifold as defined by the bottom of bore 11 it can only enter between the ribs 49 of manifold 39 and flow down the fin corrugations. It cannot leak laterally between the fins and tube sheets. The air seals at the fin corrugations are effected automatically in response to the brazing or soldering process by which the heat exchanger core is fabricated. The seals preclude or make unncessary a use of channel members or other means of lateral containment which might otherwise be required to be installed between the tubes 21-26 at their side margins.

Also, and as previously noted, the fin strips 36 extend above and below opposite ends of the openings 32 and are in an abutting relation to the inner face of header plate 19. In the brazing or soldering process closed off corrugations and portions of corrugations are sealingly engaged with the header plate 119 effectively preventing by-passing air flow around that end of the fin strip contacting such plate. In the fragmentary view FIG. '7, the relationship of the fin material to the plate H9 is illustrate'd.

The tube means 2l-26 may take other forms than the stacked series of individual tube elements 2'7. Each such means might, for example, be comprised of a single, tube flattened for end accommodation in slots corresponding to the slots 29 and 311. Finmaterial may or may not be inserted in such tubes for better heat transfer results. As shown in FIG, 8, each tube means could also be a plate and fin assembly made up of a fin strip 57 sandwiched between separate opposing plates 58 and 59. The parts would be soldered or brazed to a unitary form. For greater cleanability, should this be a factor, strip 57 can be made with relatively widely spaced square-like fin corrugations, as illustrated.

The invention has been disclosed with reference to particular embodiments. Structural modifications have been discussed and these and others obvious to a per son skilled in the art to which the invention relates are considered to be within the intent and scope of the invention.

What is claimed is:

ll. A cartridge design true counterflow heat exchanger of the tube and fin type, comprising a pair of spaced apart header plates, tube means interconnecting said plates and having ends opening therethrough, said tube means disposing in a parallel spaced apart relation, corrugated fin strip means interposed between said tube means and orienting to have its corrugations extend lengthwise of the tube means toward said header plates, one end of the tin strip means substantially abutting one of said header plates and the other end being longitudinally spaced from the other one of said plates, said one header plate having openings for flow of a first fluid therethrough, said fin strip means defining a flow path for said first fluid opening at one end through said openings in said. one header plate and terminating at its other end beyond said other end of said fin strip means in a space defined by said other end of said fin strip means and by said other header plate,

said space being open to the exterior of the heat exchanger, and manifold members mounting to said header plates, the one thereof mounting to said one header plate having openings aligning with the said openings in said one header plate and having in alternating relation therewith passages aligning and comm unicating with the ends ofsaid tube meansopening through said one header plate.

2. A heat exchanger according to claim 1, characterized by a manifold chamber in said one manifold member in common communication with said passages therein.

3. A heat exchanger according to claim 2, charac terized by return conduit means extending from said chamber in said one manifold member at one end of the heat exchanger in parallel relation to said tube means to the opposite end of the heat exchanger.

4. A heat exchanger according to claim 3, wherein said tubular means comprises a manifold tube and openings in said header plates in which the ends of said manifold tube are installed.

5. A heat exchanger according to claim 4, wherein the manifold member mounting to said other header plate has a manifold chamber in common communication with the ends of the tube means opening through said other header plate.

b. A heat exchanger according to claim 2, wherein said header plates have relatively narrow elongated slots receiving the ends of said tube means, said tube means having a corresponding configuration to interfit in said slots, the said openings in said one header plate being elongated in the same sense as said slots therein and beingin alternating relation thereto.

7. A heat exchanger according; to claim 6, wherein the manifold member mounting to said one header plate has spaced apart projecting portions aligning with said tube means, said passages being formed in said projecting portions and opening through an inner face of said member to register with the slots in said one header plate, the said openings in the manifold member mounting to said one header plate appearing intermediate said projections, said projections defining entrance or exit means for flow of said first fluid.

8. A heat exchanger according to claim 1, wherein said fin strip is secured to said tube means by means constituting a seal and a bond whereby to preclude bypassing flow of said first fluid laterally of said fin strip means except at said space.

9. A heat exchanger core, comprising means defining a series of laterally spaced apart tube means, each tube means presenting an expansive wall on its opposite sides, fin strip means overlying said expansive walls and held in substantially compressive contact between opposite walls of adjacent tube means, a pair of header plates each having a series of spaced apart slots accommodating the ends of said tube means and at least one of said header plates having another series of openings therein in alternating relation to said slots, said fin strip means orienting to have its corrugations extend lengthwise of said tube means toward said header plates and having an end thereof in substantially end abutting relation to said one header plate, and means effecting a sealing engagement of individual fin corrugations to the walls of said tube means and to said one header plate, a fluid flowing lengthwise of said fin strip means to enter or exit at said other series of openings being denied by-passing flow laterally of said strip means.

10. A heat exchanger core according to claim 9, wherein said fin strip means is at one end in substantially end abutting contact with one of said header plates and at its other end is in a spaced relation to the other header plate, the space between said other header plate and the saidother end of said fin strip means constituting a transverse flow spaced for the fluid entering or exiting the core by way of said other series of openings.

11. A heat exchanger according to claim 1, wherein said tube means comprises a plurality of tubes with respect to which corrugated fin strip means is in a sandwiched relation, said header plates having separate opposing slots for each tube and the said openings in said one header plate substantially aligning with ends of said fin strip means.

12. A heat exchanger according to claim 11, wherein each tube is comprised of a plurality of tube elements stacked one upon another, adjacent elements presenting broad flat surfaces for contact with one another and combining to define substantially continuous expansive side surfaces for contact with said fin strip means.

13. A heat exchanger according to claim 11, wherein each tube is comprised of a single tube flattened to a laterally elongated shape for end accommodation in said slots and unitarily to define expansive side surfaces for contact with said fin strip means.

14. A heat exchanger according to claim 11, wherein each tube is comprised of opposing spaced apart plate elements and an intervening fin strip, said plate elements and tin strip being bonded together. 

1. A cartridge design true counterflow heat exchanger of the tube and fin type, comprising a pair of spaced apart header plates, tube means interconnecting said plates and having ends opening therethrough, said tube means disposing in a parallel spaced apart relation, corrugated fin strip means interposed between said tube means and orienting to have its corrugations extend lengthwise of the tube means toward said header plates, one end of the fin strip means substantially abutting one of said header plates and the other end being longitudinally spaced from the other one of said plates, said one header plate having openings for flow of a first fluid therethrough, said fin strip means defining a flow path for said first fluid opening at one end through said openings in said one header plate and terminating at its other end beyond said other end of said fin strip means in a space defined by said other end of said fin strip means and by said other header plate, said space being open to the exterior of the heat exchanger, and manifold members mounting to said header plates, the one thereof mounting to said one header plate having openings aligning with the said openings in said one header plate and having in alternating relation therewith passages aligning and communicating with the ends of said tube means opening through said one header plate.
 2. A heat exchanger according to claim 1, characterized by a manifold chamber in said one manifold member in common communication with said passages therein.
 3. A heat exchanger according to claim 2, characterized by return conduit means extending from said chamber in said one manifold member at one end of the heat exchanger in parallel relation to said tube means to the opposite end of the heat exchanger.
 4. A heat exchanger according to claim 3, wherein said tubular means comprises a manifold tube and openings in said header plates in which the ends of said manifold tube are installed.
 5. A heat exchanger according to claim 4, wherein the manifold member mounting to said other header plate has a manifold chamber in common communication with the ends of the tube means opening through said other header plate.
 6. A heat exchanger according to claim 2, wherein said header plates have relatively narrow elongated slots receiving the ends of said tube means, said tube means having a corresponding configuration to interfit in said slots, the said openings in said one header plate being elongated in the same sense as said slots therein and being in alternating relation thereto.
 7. A heat exchanger according to claim 6, wherein the manifold member mounting to said one header plate has spaced apart projecting portions aligning with said tube means, said passages being formed in said projecting portions and opening through an inner face of said member to register with the slots in said one header plate, the said openings in the manifold member mounting to said one header plate appearing intermediate said projections, said projections defining entrance or exit means for flow of said first fluid.
 8. A heat exchanger according to claim 1, wherein said fin strip is secured to said tube means by means constituting a seal and a bond whereby to preclude by-passing flow of said first fluid laterally of said fin strip means except at said space.
 9. A heat exchanger core, comprising means defining a series of laterally spaced apart tube means, each tube means presenting an expansive wall on its opposite sides, fin strip means overlying said expansive walls and held in substantially compressive contact between opposite walls of adjacent tube means, a pair of header plates each having a series of spaced apart slots accommodating the ends of said tube means and at least one of said header plates having another series of openings therein in alternating relation to said slots, said fin strip means orienting to have its corrugations extend lengthwise of said tube means toward said header plates and having an end thereof in substantially end abutting relation to said one header plate, and means effecting a sealing engagement of individual fin corrugations to the walls of said tube means and to said one header plate, a fluid flowing lengthwise of said fin strip means to enter or exit at said other series of openings being denied by-passing flow laterally of said strip means.
 10. A heat exchanger core according to claim 9, wherein said fin strip means is at one end in substantially end abutting contact with one of said header plates and at its other end is in a spaced relation to the other header plate, the space between said other header plate and the said other end of said fin strip means constituting a transverse flow spaced for the fluid entering or exiting the core by way of said other series of openings.
 11. A heat exchanger according to claim 1, wherein said tube means comprises a plurality of tubes with respect to which corrugated fin strip means is in a sandwiched relation, said header plates having separate opposing slots for each tube and the said openings in said one header plate substantially aligning with ends of said fin strip means.
 12. A heat exchanger according to claim 11, wherein each tube is comprised of a plurality of tube elements stacked one upon another, adjacent elements presenting broad flat surfaces for contact with one another and combining to define substantially continuous expansive side surfaces for contact with said fin strip means.
 13. A heat exchanger according to claim 11, wherein each tube is comprised of a single tube flattened to a laterally elongated shape for end accommodation in said slots and unitarily to define expansive side surfaces for contact with said fin sTrip means.
 14. A heat exchanger according to claim 11, wherein each tube is comprised of opposing spaced apart plate elements and an intervening fin strip, said plate elements and fin strip being bonded together. 